The human brain works much harder when playing sport against robots, scientists have found.
Researchers from the University of Florida analysed dozens of hours of table tennis matches where humans were pitted against machines and each other.
Players wore electrode caps so their brain activity could be monitored during the games.
Scientists found that when playing against each other, the players’ brains worked in unison, “like they were all speaking the same language”.
Daniel Ferris, a professor of biomedical engineering at the University of Florida, said: “If we have 100,000 people in a football stadium and they’re all cheering together, that’s like synchronisation in the brain, which is a sign the brain is relaxed.
“If we have those same 100,000 people but they’re all talking to their friends, they’re busy but they’re not in sync.
“In a lot of cases, that desynchronisation is an indication that the brain is doing a lot of calculations as opposed to sitting and idling.”
The researchers said their work, published in the journal eNeuro, shows that the brain works harder when playing against robots because machines do not provide any cues about what they are going to do next.
Prof Ferris, who is one of the study authors, said: “Humans interacting with robots is going to be different than when they interact with other humans.
The researchers said that as robots grow more common and sophisticated, understanding how the human brain responds to an opponent’s moves could allow engineers to design robots to be more naturalistic.
Amanda Studnicki, a graduate student at the University of Flordia, who was part of the research team, said: “I still see a lot of value in practising with a machine.
“But I think machines are going to evolve in the next 10 or 20 years, and we could see more naturalistic behaviours for players to practise against.”
The research is published in the journal eNeuro.